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      <title>Kafka 中 Zookeeper 的作用 - 交互式测验</title>
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            <div class="quiz-header">
              <h1>Kafka 中 Zookeeper 的作用 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
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      <script>
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  {
    "question": "根据文档，Zookeeper在Kafka集群中扮演的最核心、最根本的角色是什么？",
    "options": [
      "作为数据备份中心，定期归档Kafka中的消息。",
      "直接处理生产者发送的消息和消费者拉取的请求。",
      "作为协调和管理服务，维护集群元数据、负责领导者选举和监控节点。",
      "为Kafka集群提供网络路由和负载均衡功能。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Zookeeper的核心作用是作为Kafka集群的协调与管理中心。它不直接处理消息数据，而是管理集群的元数据（如主题、分区信息）、协调领导者选举、监控节点状态等，从而保证整个集群的稳定和可靠运行。",
    "source": "文档中「协调和管理」部分",
    "hint": "文档开篇就总结了Zookeeper的定位，它被描述为Kafka的一个“基础设施”，扮演着关键的协调角色。"
  },
  {
    "question": "在Kafka中，当一个分区的领导者（leader）节点发生故障时，Zookeeper是如何确保系统继续可用和一致的？",
    "options": [
      "Zookeeper会暂停该分区的所有读写操作，直到管理员手动指定一个新的领导者。",
      "Zookeeper会协调并启动新一轮的领导者选举过程，从存活的副本中选出新的领导者。",
      "Zookeeper会将故障节点的请求自动转发给集群中负载最低的节点。",
      "Zookeeper会立即将所有分区的领导权都转移到控制器节点上。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "当现有领导者宕机时，Zookeeper的核心职责之一就是协调新一轮的领导者选举。它会确保只有一个新的领导者被从存活的副本中选举出来，并将这个结果通知给集群中的所有相关节点，从而快速恢复分区的正常读写功能，保证了系统的高可用性。",
    "source": "文档中「领导者选举」部分",
    "hint": "思考一下当“首领”不在时，系统需要一个怎样的机制来推选出新的“首领”以维持秩序。"
  },
  {
    "question": "以下哪一项信息不属于Zookeeper为Kafka存储的元数据（Metadata）？",
    "options": [
      "每个主题的分区数量和副本分配列表。",
      "消费者组的名称及其消费的偏移量（offset）信息。",
      "生产者发送到Topic中的具体消息内容。",
      "集群中哪个节点是当前的控制器（Controller）节点。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Zookeeper负责存储Kafka集群的元数据，这包括主题信息、分区分配、消费者组状态、控制器节点信息等。但是，它不存储业务数据，即生产者发送的具体消息内容。消息内容是存储在Kafka Broker自身的磁盘日志文件中的。",
    "source": "文档中「存储元数据」部分",
    "hint": "元数据是“关于数据的数据”，它描述了系统的结构和状态，而不是系统处理的业务数据本身。"
  },
  {
    "question": "文档中提到，Kafka利用Zookeeper的分布式锁服务来保证关键操作的原子性。这个“关键操作”最典型的例子是什么？",
    "options": [
      "确保领导者选举过程中只有一个节点能够成功发起并完成选举。",
      "锁定某个消息，防止多个消费者同时消费。",
      "在创建主题时，锁定集群所有节点以防止写入冲突。",
      "确保生产者发送的每一条消息都被原子性地写入磁盘。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档明确指出，Zookeeper的分布式锁服务在领导者选举中扮演着至关重要的角色。在选举过程中，每个候选节点会尝试获取分布式锁，只有成功获取锁的节点才有资格成为新的领导者。这确保了选举过程的原子性和一致性，避免了“脑裂”（即出现多个领导者）问题的发生。",
    "source": "文档中「分布式锁」部分",
    "hint": "在“领导者选举”和“分布式锁”两个章节中都提到了一个共同的应用场景。"
  },
  {
    "question": "管理员想要动态地调整某个Kafka主题的副本数量，根据文档描述，这个配置信息存储在哪里，并由谁来管理？",
    "options": [
      "存储在每个Broker节点的本地配置文件中，需要重启Broker才能生效。",
      "存储在Zookeeper中，允许管理员动态读取和更新。",
      "存储在Kafka客户端的配置中，由生产者决定。",
      "这是一个固定配置，一旦主题创建后便无法更改。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档在“协调和管理”部分的“动态配置管理”中提到，Kafka的一些配置参数（如分区的副本数、主题配置信息）存储在Zookeeper中。这使得管理员可以对集群进行灵活的配置管理，动态地更新这些参数而无需重启整个集群。",
    "source": "文档中「协调和管理」部分的「动态配置管理」",
    "hint": "文档提到了一个特性，允许管理员对集群进行“灵活的配置管理”。"
  },
  {
    "question": "当一个Kafka Broker节点与Zookeeper失去连接时，根据Zookeeper的监控机制，可能会触发什么后果？",
    "options": [
      "Zookeeper会尝试重启该Broker节点的进程。",
      "Zookeeper会通知所有生产者停止向该Broker节点上的分区发送数据。",
      "该Broker节点会被视为宕机，Zookeeper会触发相应的故障处理机制，如为它所领导的分区重新进行领导者选举。",
      "不会有任何影响，只要该Broker节点自身还在运行，它就会继续处理请求。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Zookeeper负责监控Kafka集群中各个节点的连接状态。一旦某个节点与Zookeeper的会话超时或断开连接，Zookeeper会认为该节点已宕机。这个事件会通知到集群中的其他节点（特别是控制器节点），并触发一系列故障恢复流程，例如为该节点之前作为领导者的分区选举新的领导者。",
    "source": "文档中「监控和管理」部分的「节点连接状态管理」",
    "hint": "Zookeeper如何感知节点的“生死”？当它认为一个节点“死亡”后，集群需要做什么来弥补这个空缺？"
  },
  {
    "question": "在Kafka集群中，存在一个特殊的“控制器节点”（Controller），它负责管理分区的领导者选举等操作。集群中的其他节点是如何知道哪个节点是控制器节点的？",
    "options": [
      "通过读取本地的静态配置文件来确定。",
      "控制器节点会定期向所有其他节点广播自己的身份。",
      "第一个启动的Broker节点自动成为永久的控制器节点。",
      "控制器节点的信息存储在Zookeeper中，其他节点通过访问Zookeeper来获取。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档在“存储元数据”一节中明确指出，Zookeeper存储了控制器节点的信息。集群中的所有Broker节点都会在Zookeeper上监听一个特定的znode（例如 /controller），以实时了解当前哪个Broker是控制器，并与之通信来接收管理指令。",
    "source": "文档中「存储元数据」部分的「控制器节点信息」",
    "hint": "这个问题的答案是Zookeeper存储的一种非常关键的元数据，它关系到整个集群的管理权归属。"
  }
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                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  